This invention relates to the treatment of articles or workpieces by means of subjecting them to media impingement; for example, the treatment of turbine blades by shot peening. More particularly, this invention relates to mechanism for manipulating the articles or workpieces within the path or stream of gravity accelerated media such as steel shot.
The present invention is related to the apparatus as disclosed in patent application Ser. No. 300,948, entitled GRAVITY ACCELERATED SHOT TREATING APPARATUS, filed Sept. 10, 1981, and having inventors and the assignee in common with the above-identified patent application, apparatus for shot peening comprises the impacting of articles or workpieces with uniformly sized spherical steel shot accelerated by the force of gravity created by the shot freely falling in space.
In such patent application, a perforated plate or screen is provided from which the shot falls on the article or workpiece to be treated. The object of the method and apparatus disclosed in such patent application is to uniformly treat predetermined surfaces of the workpieces in a uniform manner so that each workpiece is subjected to the same peening intensity. Also, it is important that in certain workpieces, such as turbine blades, the workpiece be oriented properly, i.e., that certain surfaces be exposed to the impact of the shot without deleterious effect on other parts of the blade. This requires that the workpiece be rotationally oscillated to allow uniform finishing of the thin contoured pieces of airfoil configuration. Further, the impingement angle of the shot is important and, therefore, it is necessary that the blades be arranged at a predetermined angle as they are oscillated. The angle at which the blade is held in the stream varies with its shape, particularly when irregular shapes such as shoulders and the like are to be peened.
Also, as disclosed in the above-identified application, it is desirable to uniformly shot peen a multiple of workpieces in one operation. Consequently, there has been a need for an improved mechanism for holding and manipulating the workpieces within the stream of the treating media, it being important that the workpieces can be rotated and the inclination thereof varied for treating the surfaces of a variety of different shapes and sizes of workpieces.